1. Technical Field
The present invention relates to a high-pressure fuel injection pipe generally provided and used as a fuel supply channel in a diesel internal combustion engine and formed of a relatively thick and small-diameter metallic pipe and, more specifically, to a high-pressure fuel injection pipe which can alleviate concentration of a stress to an under-head portion at the terminal due to a bending load or the like caused by vibrations.
2. Background Art
In the background art, there is a known high-pressure fuel injection pipe of this type formed of a thick and small-diameter metallic pipe 11 provided at the end thereof with a connecting head portion 13 of a truncated arcuate shape having a spherical pressing seat surface 12 on its outer periphery formed by buckling molding. The high-pressure fuel injection pipe of this type is connected by loosely fitting a ring-shaped washer 15 or a sleeve washer (not shown) to a pipe diameter portion 14 of the thick and small-diameter metallic pipe 11 itself which constitutes an under-head portion of the connecting head portion 13, engaging in this state the back surface of the connecting head portion 13 to the bottom wall surface inside a tightening nut 16 assembled via the washer 15, being pressed against the seat surface of a pipe joint (not shown) of a holder on the partner side or a pump when screwing and tightening thereto.